There is a trend in the art to provide electrical connectors having smaller dimensions, for e.g. providing multiple connectors in a restricted building space. However, with the electrical connectors becoming smaller and smaller, the electrically conductive inlays of those electrical connectors, i.e. the electrical contact pins and/or the electrical contact terminals, have to become smaller as well.
Wherein electrical contact pins can be manufactured with smaller dimensions (i.e. smaller cross section) very easily, it is more challenging to provide electrical contact terminals having smaller dimensions. The difficulties arise, since for providing smaller electrical contact terminals typically thinner metal sheets have to be used. However, providing electrical contact terminals being manufactured from thinner metal sheets, results in reduced wall thicknesses of the electrical contact terminal and thus to reduced contact forces that can be achieved between the electrical contact pin and the electrical contact terminal.
This is, because contact forces of an electrical contact terminal are typically generated by contact beams that are formed from a sheet of metal, wherein the contact beams are preferably integrally formed with the electrical contact terminal. Thus, the contact force that can be applied by a contact beam of an electrical contact terminal on an electrical contact pin is strongly dependent on the material used, i.e. the sheet material, and the sheet thickness. Consequently, with merely providing smaller terminals, the contact force applied on the electrical contact pin will become smaller. However, the smaller electrical contact terminals have to fulfill the same contact force requirements, i.e. they have to apply the same contact forces on the electrical contact pin, as electrical contact terminals that are manufactured from conventional thick sheet materials.
Generally, high contact forces are desired in electrical connectors (independent of the connector size), to provide a secure electrical contact between the electrical contact pin and the electrical contact terminal, since a higher contact force will reduce the contact resistance of the electrical contact. Further, with increasing the contact force, the connectors are less prone to environmental conditions, such as vibrations, shock and/or the like. Thus, the field of application of the connectors having a high contact force can be broadened.
In the art, electrical contact terminals 100 are known, as shown in FIG. 1, that are provided with a contact beam 120, being supported by a support beam 142, to provide increased contact forces between the electrical contact terminal 100 and the electrical contact pin 110 that can be received in the electrical contact terminal 100. Due to the stacked arrangement of the contact beam 120 and the support beam 142, both beams 120, 142 have to be deflected, when the pin 110 is received in the electrical contact terminal 100, thereby increasing the contact force FN. However, in the known electrical contact terminal 100, the contact force is directly dependent on the sheet material thickness used. Thus, the required contact force limits the minimal sheet thickness so that terminals being provided with stacked contact and support beams 120, 142 cannot be provided at very small dimensions. Respectively, if thin sheets are used, the required contact force cannot be achieved.
Further, in order to increase the contact force, different sheet materials can be used, particularly sheet materials having a high stiffness, resulting in stiff electrical contact terminals. These stiff electrical contact terminals can generate high contact forces on an electrical contact pin, received therein. However the contact force will increase rapidly with increased deflection of the contact and/or support beam(s), e.g. due to variations of the dimensions of the electrical contact pins used. Therefore the contact force and the pin insertion force, i.e. the force that is required to insert an electrical contact pin into the electrical contact terminal, strongly depend on the dimensions of the electrical contact pin. This is not desirable, since a certain contact force has to be achieved. Further, varying pin insertion forces make automated pin insertion and surveillance more difficult. Particularly, high pin insertion forces hinder the insertion of the electrical contact pin and increase the risk of damaging the electrical contact pin and/or the electrical contact terminal during pin insertion.
Still further, using stiff contact terminals results in high stress levels, particular at the contact and support beams. If an electrical contact pin is inserted improvidently, e.g. due to high required pin insertion forces, the terminal can be damaged, e.g. by plastic deformation.
Therefore, there is a need in the art to provide electrical contact terminals that can provide a high contact force, even if small dimensions of the terminal are required. Further, the electrical contact terminals shall be configured to provide a desired high contact force, while pin insertion forces are moderate. Still further, the contact force and/or the pin insertion force shall have small tolerances.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.